Gas content measurement is a principal tool for the assessment and management of outburst risk by the Australian underground coal industry. While the fast desorption technique is widely used for gas content measurement, concerns have been raised regarding the reproducibility of results between different laboratories. This resulted in an Australian Coal Association Research Program (ACARP) supported study completed in 1998. Undividual laboratories were performing well but their results were not being consistently reproduced at other laboratories, with variability of up to 17%. A further project aimed to determine the source(s) of the variability between laboratories and to propose modifications to the fast desorption test method. Possible mechanisms associated with individual laboratory practices were identified as: 1) Variable partial pressure conditions at the end of the measurement. 2) Temperature rise during crushing, creating an overestimate of gas content. 3) Dissolution of carbon dioxide in water, leading to underestimation of gas content and 4) Oxidation of the coal during the measurement, particularly in the crushing phase, most likely leading to an underestimate of gas content. It was also recognised that sampling techniques for the coal can also lead to variability in results.